Electric rivet heater



Oct- 13, 1925- o. A. COLBY ELECTRIC RIVET HEATER 3 Sheets-Sheet 1INVENTOR 0rd .fid BY 4 *1 0 ATT RNEY Filed Sept. 1'7, 1920 yaw! Oct. 13,1925- 1,557,026

0. A. COLBY ELECTRIC RIVEI HEATER Filed Sept. 17, 1920 3 Sheets-Sheet 3WITNESSES: INVENTOR zeal M TORNEY Patented Oct. 13, 1925.

UNITED STATES PATENT OFFICE.

on A. COLBY, OI IRWIN, PENNSYLVANIA, ASSIGNOB '10 WESTINGHOUSE ELECTRICQ IANUIAC'IURING COIPANY, A CORPORATION OF PENNSYLVANIA.

ELECTRIC HEATER.

Application filed September 17, 1920. Serial No. 410,863.

To all whom it may concern:

Be it known that I, ORA A. COLBY, a citizen of the United States, and aresident of Irwin, in the county of Westmoreland and State ofPennsylvania, have invented a new and useful Im rovemcntin ElectricRivet Heaters, of which the following is a specifi- .cation.

My invention relates to electric rivet heating machines wherein therivets are heated by the passage of electric current through them.

One object of my invention is to provide an electric rivet heatingmachine that shall be adjustable for heating rivets of various sizes,that shall automatic-ally limit the tem perature to which the rivet isheated, and that shall be provided with means for simultaneouslycontrolling the pressure applied to the rivet and the circuit of thetransformer connected to the machine.

In heating rivets by connecting them to an electric circuit, it is verydesirable to adjust the contact terminals connected to the rivet forefliciently heating rivets of various sizes, and, moreover, it isdesirable to apply a variable pressure to the rivets during the heatingoperation. Suitable pressure should be applied to the ends of the rivetsduring the heating operation either to prevent burning of the ends ofthe rivet or to prevent buckling of the same. If an insufiicientpressure is applied to the ends of the rivets, burning of the rivet endsis very liable to occur and if an extreme pressure is applied to therivets a crushing or buckling of the rivet is likely to occur.

In an electric rivet heating machine constructed in accordance with myinvention, a transformer is provided having two primary coils which maybe connected to a supply circuit either in parallel or in series circuitrelation. An open circuit secondary winding is located between the twoprimary coils and is provided with two removable contact terminalsbetween which the rivet to be heated is placed.

The two contact terminals are relatively movable for heating varioussize rivets in the machine and a treadle member is provided not only forapplying pressure to the rivet being heated but also for controlling thecircuit of the transformer for the machine. The treadle memberis soconnected to the contact terminals by spring members as to limit thepressure which is applied to the rivet. The treadle member also controlsa small auxiliary switch which governs the main switch for connectingthe transformer to the supply circuit.

A thermal device comprising a bimetallic strip is disposed adjacent tothe rivet being heated for controlling the main switch in accordancewith Uhe tem rature of the rivet. Thus, when the rivet 1s heated to apredetermined temperature, the thermal device operates the main switchto disconnect the transformer from the supply circuit. The contactpoints which are mounted on the contact terminals of the transformer andwhich engage the rivet to be heated are detachably connected to suchterminals. Moreover, one of the contact points is provided with aconcave engaging surface and the other contact point is provided with aconvex engaging surface. Such engaging surfaces are provided in order toinsure the even heating of the head and the bottom of the rivet.

In the accompanying drawings:

Figure 1 is a front elevational view of a machine constructed inaccordance with my invention;

Fig. 2 is a sectional view along the line IIII of Fig. 1;

Fig. 3 is a bottom plan view of the ma chine shown in Fig. 1;

Fig. 4 is a diagrammatic view of the circuits connected to the machine;

Fig. 5 is a detail view of the thermal device;

Fig. 6 is a detail view of the clamp for one of the contact terminals;

Fig. 7 is a detail view of the racks and pinions for operating one ofthe contact terminals;

Fi 8 is a detail view of a rivet in position between the contactterminals, and

Fig. 9 is a detail view of the friction means ap lied to the pinionshaft.

eferring to the drawings a machine 1 is provided with a frame 2 composedof four angle irons 3 which are held together by three platforms 4, 5and 6. Such platforms are preferably com osed of angle irons, as shownin Fig. 2 o the drawings, and are connected to the angle irons 3, in anysuitable manner. The sides and rear, and a portion of the front of theframe 2 is enclosed by sheet metal 7. The frame 2 is bolted to twowooden blocks 8, in order to not only support the machine but also toinsulate it from any surface upon which it may be resting. Preferably,the machine is employed in the ship-building industry, and in such case,it is desirable to insulate the machine from the steel decks of theship.

The platform 4, which 18 located near the bottom of the frame, supportsthe treadle member 9. The platform 5, .which is located near the centralpart of the frame, carries a transformer 10 and the latform 6, which islocated near the top of t e frame carries a pivoted lever 11, for apurpose to be hereinafter set forth.

The transformer 10 comprises two primary coils 12 and 13, which aremounted on a core member 14, and a secondary winding 15 which isdisposed between the primary coils 12 and 13. The core member 14 issecured to the platform 5, in any suitable manner, as b means of angleirons 16. The core mem r 14 is refera 1y composed of laminated steel anthe seconds winding is preferably composed of lam1- nated cop r.

The contact terminal 17, which is composed of brass or copper isconnected to one terminal of the secondary winding 15 by means of bolts18. The contact terminal 17 carries a contact point 19 which engages thehead of the rivet to be heated.

A member 20, which is preferably composed of copper, is not onlyconnected to the platform 5 by the bolts 21, but is also connected toone terminal of the secondary winding 15 by means of bolts 22. Adjacentto the member 20 is rovided a sliding contact member 23 which ispreferably composed of copper or any other suitable conductin material.The contact member 23 is hel in position adjacent to the member 20 bymeans of a cover 24, as shown in Fig. 6 of the drawings. The cover 24 isconnected to the member 20 by means of bolts 25 and is rovided with ashoulder portion 26 for ho ding the contact member 23 in en gement withthe member 20.

e contact member 23 carries a contact ppint 27 for engaging the rivet 28that is ing heated, a thermal device 29, a clamping device 30, and tworack members 31 and 32, which serve a purpose to be hereinafter setforth.

The contact point .27 is threadably connectedto the contact member 23and carries an enga ing surface which is concave in form. 0 contactpoint 19 is threadably connected to the contact terminal 17 and carriesan engaging surface which is convex in form. It is n to provide theconvex and the concave engaging surfaces for the contact points as shownin Fi 8, in order to insure the even heating 0 the head and the bottomof the rivet.

The clampin means 30, which is shown in Figs. 2 an 6, of the drawings,comprises a rod 33 which'is threadably connected to the contact member23 and which carries a collar portion 34. The collar rtion 34 enga ablock member 35. he block mem r 35 permits the free rotation of the rod33 and is held in position adjacent to the contact member 23 by means ofthe shoulder rtions of the cover 24.

When e rod 33 is turned in a direction to unscrew it from the contactmember 23, the collar portion 34 en es the block member 35 which, inturn, cross the contact member 23 into engagement with the member 20.

A small shaft 36, which is moun v n the cover member 24 as shown in 2and 7 of the drawings, carries two pinions 37 and 38 which mesh with thetwo rack members 31 and 32. A suitable operating handle 39 is mounted onthe shaft 36 for operating the pinions 37 and 38 for rais' or loweringthe contact member 23, mo mg to the size of the rivet to be heated. Inor er to effect the free movement of the contact member 23 by the oratin handle 39, it is first necessary to reease t e clamping device 30.

In order to prevent the sudden drop ing of the contact member 23 uponthe release of the clampin device 30, a friction means 40, shown 11] ig.9, is provided for preventin the free rotation of the shaft 36. Thefrlction means com rises a member 41 compowd of any suitab e frictionmaterial which is held in engagement with the shaft 36 by means of abolt 42. The pressure of the bolt on the member 41 may be so adjusted asto prevent the movement of the contact member 23 upon the release of theclamping device 30.

The thermal device 29, which is shown in Fig. 5 of the, drawings,comprises a bimetallic strip 43 which is mounted on, and insulated from,a support 44 and which operates bet-ween two contact members 45 and 46.The contact members 45 and 46 are mounted upon a. support 47. A. shieldmember 48 is mounted upon the two supports 44 and 47 adjacent to therivet 28 which is being heated. The shield 48 is provided with anadjustable opening 49 which is varied in accordance with the size of therivet that is being heated. The thermal device 29 serves to control amain switch 50 which connects the transformer 10 to the supply circuit.

A switchrd 51 is mounted on the frame 2, in any suitable manner, and isdisposed below the platform 5, as shown in Fig. 2 of the drawn Theswitch-board carries the main switc 50 for connecting the two primarycoils 12 and 13 of the transformer to a supply circuit comprisingconductors 52 and 53. Two fuse members 54 and 55 and a double-throwswitch 56 are connected in circuit with the transformer.

The switch 56 serves to connect the primary coils 12 and 13 of thetransformer either in parallel or in series circuit relation. The switch50 comprises contact members 57 and an operating coil 58 which iscontrolled not only by means of the thermal device 29 but also by meansof an auxiliary switch 59. The auxiliary switch 59 is controlled by thetreadle 9. If desired, taps may be extended from the primary colls forvarying the electrical characteristics of the secondary circuit.

A transfer switch 60 is controlled by the thermal device 29 foreffecting operation of the main switch 50 and is preferably mounted onthe switch-board 51. The transfer switch 50 comprises two coils 61 and62 which move a contact member 63 into engagement with stationarycontact members 64 and 65. A switch 66 is mounted on the switch-board 51for effecting control of the switch 50 independent of the thermal device29.

The treadle 9 comprises a frame 67 which is pivotally mounted on twomembers 68 whlch in turn are supported on the bottom platform 4. Theframe 67 extends beyond the frame of the machine in order 'to beconveniently operated by the foot of the operator. The rear portion ofthe frame is pivotally connected to a rod or pipe 69, in any convenientmanner, as shown in Figs. 2 and 3 of the drawin A yoke member 7( isconnected to the frame 67 for operating the auxiliary switch 59, inaccordance with the operation of the treadle. The yoke member 70 carriesa bolt 71 which engages a ush button 72 for directly operating a switch59. The push button 72 is mounted on, and the swltch 59 is mountedwithin, a casing 7 3 which is suitably mounted on the platform 4.

The rod 69 which is connected to the treadle frame 67 telescopes with arod 75, which is pivotally connected to the lever 11. A spring member 76is mounted on the rod 75 between two nuts 77 on the rod 75 and a collar78 on the rod 69. Such spring member 76 serves to effect a resilientconnection between the two rods. A second spring member 79 is mounted onthe rod 75 between the platform 5 and a set of nuts 80. The springmember '79 serves to bias the treadle to a raised or inoperativeposition.

The lever 11 comprises two bars which are' ivotally mounted on a block81. The bloc 81 is supported on the platform 6 in any suitable manner. Alink 82, which is composed of any suitable insulating material, isprovided for connecting the lever 11 with the contact terminal 17.

A cover plate 83 is mounted on the top of the frame of the machine,.inan suitable manner, and is provided with ared side portions 84 in orderto permit the free circulation of air throu h the machine.

The operation of tie machine above described 1s as follows:The contactmember 23 is adjusted by the clamping device 30 and the crank 39 for anycertain size of rivets, and a rivet 28 is placed in the machine betweenthe contact points 19 and 27, as shown in Figs. 1 and 2 of the drawin s.The frame 67 of the treadle 9 is operated y the foot of the operator toapply pressure to the rivet through the rods 69 and 75 and the lever 11.Simultaneously, the treadle operates the auxiliary switch 59 to connectthe transformer to the supply conductors 52 and 53.

Upon operation of the switch 59, a circuit is completed from the supplyconductor 52 through the switch 59, energizing coil 58 of the mainswitch 50 and the contact member 63 of the transfer switch 60 to thesupply conductor 53. Thereupon, the switch 50 is operated for connectinga transformer 10 to the supply circuit.

The spring member 76, which opposes the action of the spring member 7 9,maintains a suitable pressure upon the rivet being heated. The tensionof the spring 76 may be adjusted by means of the nuts 77.

When the rivet is heated to a predetermined temperature, the bimetallicstrip 43 of the thermal element 29 is moved out of engagement with thecontact member 46 into engagement with the contact member to complete acircuit which extends from the supply conductor 52 through the switch59, bimetallic element 43, contact terminal 45, energizing coil 62,contact terminal 65, and the contact member 63 of the trans fer switch60 to the supply conductor 53.

Thereupon the contact member 63 of the transfer switch is moved fromengagement with the contact terminal 65 into engagement with the contactterminal 64. The circuit of the energizing coil 58 for the main switchis broken and the transformer 10 is de-energized. Upon removal of therivet, which has been heated, the bimetallic element 45 engages thecontact terminal 46 for completing a circuit through the switch 59 toenergize the coil 61 upon the next operation of the treadle. The energizing coil 61 of the transverse switch moves the contact member 63 intoengagement with the contact terminal for completing the energizingcircuit of the coil 58.

The secondary winding of the transformer 10 comprises a single turnwhich is connected to the contact terminals that engage the rivet. Thesecondary circuit extends from the head of the rivet through the contactpoint 19, contact terminal 17, secondary laminations 15, contact membercuit and 20, contact terminal 23, and the contact point 27 to the bottomof the rivet 28. By

reason of the single turn secondar winding a ve hea current is cause toflow throu gli the rivet which softens it in a very short time.

Modifications in the machine, and in the construction and arrangement ofparts may be made within the s irit and scope of my invention, and sucmodifications are intended to be covered by the appended claims.

, What I claim as my invention is:

1. In a rivet heating machine, the combination comprising means forcompleting an electric circuit through the rivet to be heated, and meansfor automatically opening the circuit upon heating of the rivet to apredetermined temperature.

2. In a rivet heating machine, the combination with a transformerconnected to a supply circuit and means for connecting the rivet to beheated in circuit with said transformer and for applyin a variablepressure to the rivet, of means or automatically opening the circuit ofthe transformer upon heating the rivet to a predetermined temperature.

3. In a rivet heating machine, the combination with an electric circuitadapted to be connected to the rivet and means for applying a variablepressure to the rivet, of means for automatically opening said circuitupon heating the rivet to a predetermined temperature.

4. In a rivet heating machine, the combination with a transformer havingan open circuit secondary winding and means for connecting the rivetacross the terminals of said secondary winding, of means for connectinsaid transformer to a supply ciror automatically opening the circuit ofthe transformer upon heating the rivet to a predetermined temperature.

5. In a rivet heating machine, the comcuit of said transformer uponheating the rivet to a predetermined tem rature.

6. In a rivet heating mac e, the combination with a transformer havingtwo primary coils and an open circuit secondary w1 nd1n located betweenthe two primary coils, t open circuit in said secon winding bein closedby the rivet to be beat ed, of a supp y circuit, switching means forconnecting said primary coils in series and in parallel circuitrelation, a main switch for connecting said transformer to the su plycircuit, and means comprising a tre e member for controlling thepressure applied to the rivet and for governing the operation of saidmain switch.

7. In a rivet heating machine, the combination comprising a transformerhaving an open circuit secondary and contact terminals connected to thesecondary winding and engagingsthe rivet to be heated, one of saidtermina having a convex enga g surface and the other contact terminaling a concave engaging surface.

In a rivet-heating machine, the combination with. means for completingan electric circuit through the rivet to be heated and means comprisinga, thermostatic stri for interrupting the circuit gen heating 0 therivet to a predetermin temperature, of means for limiting the amount ofheat energy received elzy said thermostatic strip to a predeterminvalue.

In testimony whereof, I have hereunto subscribed my name this first dayof September 1920.

ORA A. COLBY.

tobe.

